In this paper we present simtools, a software to create virtual networks of UML machines which is based on UML and VNUML. Simtools allows easily building virtual scenarios, and it is a quite simple and straighforward tool for teaching networking. In fact, we are using it in some of our subjects related to networking at the Network Engineering Department at the Universitat Politecnica de Catalunya (UPC)

In this paper we describe a method for transmitting H.264/AVC encoded video. The data transfer is performed by adapting data transmission to network performance in order to ensure continuous transmission. The data transfer between server and client terminals is performed by TCP sockets. The original video is encoded in H.264/AVC for different levels of bitrate using the GStreamer library. Then each encoded video is segmented at GOP level. The purpose of segmenting the video is to facilitate switching between different video qualities to adapt the bitrate to the variable network capacity, and using a control
in the server side. Segmenting the encoded video has the
advantages of scaling the digital video service and the maximum use of network resources.

Security is vital for the reliable operation of vehicular ad hoc networks (VANETs). One of the critical security issues is the revocation of misbehaving vehicles. While essential, revocation checking can leak private information. In particular, repositories receiving the certificate status queries could infer the identity of the vehicles posing the query and the target of the query. An important loss of privacy results from this ability to tie the checking vehicle with the query's target, due to their likely willingness to communicate. In this paper, we propose an Efficient and Privacy-Aware revocation Mechanism (EPA) based on the use of Merkle Hash Trees (MHT) and a Crowds-based anonymous protocol, which replaces the time-consuming certificate revocation lists checking process. EPA provides explicit, concise, authenticated and unforgeable information about the revocation status of each certificate while preserving the users' privacy. Moreover, EPA reduces the security overhead for certificate status checking, and enhances the availability and usability of the revocation data. By conducting a detailed performance evaluation, EPA is demonstrated to be reliable, efficient, and scalable.

Future networks will be formed by millions of devices, many of them mobile, sharing information and running applications. Android is currently the most widely used operating system in smartphones, and it is becoming more and more popular in other devices. Providing security to these mobile devices and applications is a must for the proper deployment of future networks. For this reason, this paper studies the cryptographic structure and built-in tools in Android, and shows that the operating system has been specially designed for plugging-in external cryptographic modules. We conclude that the best option for providing cryptographic capabilities is using these external modules. We show the existent options and compare some features, like licensing, source code availability and price. We define some requirements, evaluate each module, and provide guidelines for developers who want to use properly security primitives.

One of the hardest tasks of a certification infrastructure is to manage revocation. This process consists in collecting and making the revocation status of certificates available to users. Research on this topic has focused on the trade-offs that different revocation mechanisms offer. Much less effort has been conducted to understand and model real-world revocation processes. For this reason, in this paper, we present a novel analysis of real-world collected revocation data and we propose a revocation prediction model. The model uses an autoregressive integrated moving average model. Our prediction model enables certification authorities to forecast the number of revoked certificates in short term.

Peer-to-peer (P2P) overlay networks have been proposed to solve routing problems of big distributed infrastructures, even for Internet scale. But the research community has been questioning the security of these networks for years. Most prior work in security services was focused on trust and reputation systems, anonymity, and secure routing. However, the proper management of identities in overlays is an important prerequisite to provide most of these security services. In this paper, we propose a protocol to control the access to a P2P overlay and to assign identities in a secure way; all this preserving the anonymity of users. This protocol involves two trusted third parties (TTPs), thanks to which it is possible to preserve the users' anonymity within the network without losing traceability. Users are authenticated by a TTP using real-world digital certificates, they select their network identifier jointly with the other TTP, and finally, the two TTPs issue the internal certificate to them. The protocol also provides revocability and protection against Sybil attacks, Eclipse attacks, whitewashers, and so on. A detailed protocol description is presented, and a performance and security analysis of the protocol is also provided. Copyright (c) 2014 John Wiley & Sons, Ltd.

This article presents a cross-layer packet scheduler to provide end-to-end QoS guarantees for Digital Video Broadcasting-Second Generation (DVB-S2) broadband satellite systems. The scheduler design is based on a cross-layer mechanism defined between the physical and the network layer. It includes an algorithm to guarantee the required QoS specifications established in the service level agreement. The algorithm calculation depends basically on two parameters: the available bandwidth present in a DVB-S2 satellite link and the QoS requirements of each traffic class defined by the satellite operator. The cross-layer scheduler's operation is demonstrated using the NS-2 simulator tool. The results show that the proposed mechanism maximizes the bandwidth utilization while enforcing the priority level of each service class when an extreme reduction of bandwidth caused by rain events is experienced. Copyright (C) 2012 John Wiley & Sons, Ltd.

This letter presents a new and simple model for a
TCP flow experiencing random packet losses due to both trans-
mission errors and congestion events. From this model, we will
derive a straightforward expression of a unified loss probability
(ULP). This ULP gives the opportunity to reuse classical analytic
models to analyze the performance of TCP and to size the buffer to
optimize the wireless link utilization. Extensive simulations using
TCP Reno in ns-2 demonstrate that our model is valid not only for
the extreme cases where either transmission errors or congestion
losses dominate but also in the situations where both types of losses
are significant.

This letter presents a new and simple model for a TCP flow experiencing random packet losses due to both transmission errors and congestion events. From this model, we will
derive a straightforward expression of a unified loss probability (ULP). This ULP gives the opportunity to reuse classical analytic models to analyze the performance of TCP and to size the buffer to optimize the wireless link utilization. Extensive simulations using TCP Reno in ns-2 demonstrate that our model is valid not only for the extreme cases where either transmission errors or congestion
losses dominate but also in the situations where both types of losses are significant.

The Vehicular Emulations Platform for Real Applications (Vespa) was
developed to allow for experiments with many vehicles running real-
world applications with real-time requirements in complex network
scenarios. A use case on the performance of video-streaming applications
demonstrates Vespa’s usefulness.

One of the critical security issues of Vehicular Ad Hoc Networks (VANETs) is the revocation of misbehaving vehicles. While essential, revocation checking can leak potentially sensitive information. Road Side Units (RSUs) receiving the certificate status queries could infer the identity of the vehicles posing the query. An important loss of privacy results from the RSUs ability to tie the checking vehicle with the query's target. We propose a Privacy Preserving Revocation mechanism (PPREM) based on a universal one-way accumulator. PPREM provides explicit, concise, authenticated and unforgeable information about the revocation status of each certificate while preserving the users' privacy.

Many peer-to-peer (p2p) overlays require certain security services which could be provided through a Public Key Infrastructure. However, these infrastructures are bound up with a revocation system, such as Certificate Revocation Lists (CRLs). A system with a client/server structure, where a Certificate Authority plays a role of a central server, is prone to suffer from common problems of a single point of failure. If only one Authority has to distribute the whole CRL to all users, perhaps several millions in a structured p2p overlay, a bottleneck problem appears. Moreover, in these networks, users often have a set of pseudonyms that are bound to a certificate, which gives rise to two additional issues: issuing the CRL and assuring its freshness. On the one hand, the list size grows exponentially with the number of network users. On the other hand, these lists must be updated more frequently; otherwise the revocation data will not be fresh enough. To solve these problems, we propose a new distributed revocation system for the Kademlia network. Our system distributes CRLs using the overlay itself and, to not compromise the storage of nodes, lists are divided into segments. This mechanism improves the accessibility, increases the availability and guarantees the freshness of the revocation data.

Wireless networks of moving objects have drawn significant attention recently. These types of networks consist of a number of autonomous or semi-autonomous wireless nodes/objects moving with diverse patterns and speeds while communicating via several radio interfaces simultaneously. To overcome current shortcomings, a number of research challenges have to be addressed in this area, ranging from initial conceptualization and modelling, to protocols and architectures engineering, and development of suitable tools, applications and services, and to the elaboration of realistic use-case scenarios by taking into account corresponding societal and economic aspects. By applying a systematic approach the objective of this book is to assess the state of the art and consolidate the main research results achieved in this area. It was prepared as the Final Publication of the COST Action IC0906 “Wireless Networking for Moving Objects (WiNeMO)”. The book contains 15 chapters and is a show-case of the main outcomes of the action in line with its scientific goals. The book will serve as a valuable reference for undergraduate students, post-graduate students, educators, faculty members, researchers, engineers, and research strategists working in this field.

Vehicular Ad Hoc Networks (VANETs) require mechanisms to authenticate messages, identify valid vehicles, and remove misbehaving vehicles. A Public Key Infrastructure (PKI) can be utilized to provide these functionalities using digital certificates. However, if a vehicle is no longer trusted, its certificates have to be immediately revoked and this status information has to be made available to other vehicles as soon as possible. The goal of this chapter is to introduce and describe in detail a certificate revocation mechanism based on the Merkle Hash Tree (MHT), which allows to efficiently distribute certificate revocation information in VANETs. For this, an extended-CRL is created by embedding a hash tree in each standard certificate revocation list (CRL). A node possessing an extended-CRL can respond to certificate status requests without having to send the complete CRL. Instead, the node can send a short response (less than 1 KB) that fits in a single UDP message. This means that any node possessing an extended-CRL, including Road Side Units (RSUs) or intermediate vehicles, can produce short certificate-status responses that can be easily authenticated. The main procedures involved in the proposed mechanism are described in detail. General security issues related to the mechanism are treated as well.

Certificate revocation is a challenging task, especially in mobile network environments such as vehicular ad Hoc networks (VANETs). According to the IEEE 1609.2 security standard for VANETs, public key infrastructure (PKI) will provide this functionality by means of certificate revocation lists (CRLs). When a certificate authority (CA) needs to revoke a certificate, it globally distributes CRLs. Transmitting these lists pose a problem as they require high update frequencies and a lot of bandwidth. In this article, we propose BECSI, a Bandwidth Efficient Certificate Status Information mechanism to efficiently distribute certificate status information (CSI) in VANETs. By means of Merkle hash trees (MHT), BECSI allows to retrieve authenticated CSI not only from the infrastructure but also from vehicles acting as mobile repositories. Since these MHTs are significantly smaller than the CRLs, BECSI reduces the load on the CSI repositories and improves the response time for the vehicles. Additionally, BECSI improves the freshness of the CSI by combining the use of delta-CRLs with MHTs. Thus, vehicles that have cached the most current CRL can download delta-CRLs to have a complete list of revoked certificates. Once a vehicle has the whole list of revoked certificates, it can act as mobile repository.

This article proposes VSPLIT, a new architecture based on TCP cross-layering and splitting techniques for optimizing the transport layer performance in vehicular networks for Internet-based Vehicle-to-Infrastructure (V2I) communications. Our architecture mainly pretends to enhance the performance of TCP handovers in 802.11 networks. VSPLIT includes a cross-layer TCP protocol, called VSPLIT-TCP, that adapts the congestion control during the handover, learning the new characteristics of the network after the handover using the mechanisms provided by the IEEE 802.21 Media Independent Handover (MIH) services. VSPLIT has been implemented and tested in the NS-3 simulator. We include the some of the most interesting performance evaluation results, which show a good performance of our proposal for the intended scenario.

This paper presents an analysis of several Transmission Control Protocol (TCP) variants working over a digital video broadcasting-second generation (DVB-S2) satellite link with the support of the Differentiated Services (DiffServ) architecture to provide quality of service (QoS). This analysis is carried out using the NS-2 simulator tool. Three TCP variants are considered: SACK TCP, Hybla TCP, and CUBIC TCP. These TCP variants are taken as a starting point because they have proven to be the most suitable variants to deal with long delays present in satellite links. The DVB-S2 link also introduces the challenge of dealing with variable bandwidth, whereas the DiffServ architecture introduces the challenge of dealing with different priorities. In this paper, we propose a DiffServ model that includes a modified queuing mechanism to enhance the goodput of the assured forwarding traffic class. This modified DiffServ model is simulated and tested, considering the interaction of the selected TCP variants. In addition, we present evaluation metrics, significant simulations results, and conclusions about the performance of these TCP variants evaluated over the proposed scenario. As a general conclusion, we show that CUBIC TCP is the TCP variant that shows the best performance in terms of goodput, latency, and friendliness.

Vehicular ad hoc networks (VANETs) are emerging as a novel paradigm for safety services, supporting real-time applications (e.g., video-streaming, Internet browsing, online gaming, etc.). However, maintaining ubiquitous connectivity remains a challenge due to both high vehicle speed, and non-homogeneous nature of the network access infrastructure. Getting access to the network infrastructure must be controlled and only authorized users should be able to use it. However, the authentication process incurs in a not-negligible delay which can result in packet losses and other issues during handoffs. Hence, a fast and secure handoff scheme is essential. Although some solutions have been given in IEEE 802.11i and 802.11r standards, the handoff latency is still above 50 ms. Other protocols such as CAPWAP and HOKEY include support for fast handoff but have not been evaluated in a vehicular network. In this article, we analyze the security properties and performance of current proposals. Finally, simulations are conducted to date the effectiveness of the handoffs schemes.

Vehicular Ad Hoc Networks (VANETs) require mechanisms to authenticate messages, identify valid vehicles, and remove misbehaving vehicles. A public key infrastructure (PKI) can be used to provide these functionalities using digital certificates. However, if a vehicle is no longer trusted, its certificates have to be revoked and this status information has to be made available to other vehicles as soon as possible. In this paper, we propose a collaborative certificate status checking mechanism called COACH to efficiently distribute certificate revocation information in VANETs. In COACH, we embed a hash tree in each standard Certificate Revocation List (CRL). This dual structure is called extended-CRL. A node possessing an extended-CRL can respond to certificate status requests without having to send the complete CRL. Instead, the node can send a short response (less than 1 kB) that fits in a single UDP message. Obviously, the substructures included in the short responses are authenticated. This means that any node possessing an extended-CRL can produce short responses that can be authenticated (including Road Side Units or intermediate vehicles). We also propose an extension to the COACH mechanism called EvCOACH that is more efficient than COACH in scenarios with relatively low revocation rates per CRL validity period. To build EvCOACH, we embed an additional hash chain in the extended-CRL. Finally, by conducting a detailed performance evaluation, COACH and EvCOACH are proved to be reliable, efficient, and scalable.

The security of the Peer-to-Peer (P2P) overlays networks has been questioned for years. Many works have been proposed to provide secure routing, anonymity, reputation systems, confidentiality, etc. However, the identity assignment has been less considered. These networks are designed so that each user has a unique identifier (nodeID), but the most of identity assignment systems allow malicious users to obtain a set of nodeIDs or even select certain identifiers. Thus, these users can disrupt the proper operation of a P2P overlay. In this paper, we propose a nodeID assignment protocol based on the issue of implicit certificates. Our purpose is to provide security services to struggle against the most of security threats in these networks with special attention to the identity assignment. This approach is based on the use of certificates and the joint generation of nodeIDs between a Certification Authority (CA) and the user. In addition, the use of implicit certificates presents certain advantages over the use of traditional certificates (explicit certificates).

In this paper we propose an architecture to provide Quality of Service (QoS) guarantees for DVB-S2 broadband satellite systems. The proposed architecture provides low complexity on its implementation and can seamlessly inter-operate with terrestrial IP networks. The solution is designed in compliance with the ETSI-BSM-QoS framework and provides a detailed design at the Satellite Independent- Satellite Dependent (SI-SD) layers in order to provide QoS guarantees by means of traffic priorities. Particularly, at the SI layers several mechanism are defined to deal with QoS differentiation based on the DiffServ framework. Conversely, at the SD layers the application of different DVB-S2 channel adaptations are assumed. The proposed architecture is evaluated using the NS-2 simulator. The key results show that the implementation of this architecture, enables to keep control of the satellite system load while guaranteeing the QoS levels for the high priority traffic classes even though bandwidth variations due to rain events are experienced.

Contributions based on cross-layer design for Quality-of-Service provisioning over DVB-S2/RCS Broadband Satellite Systems Nowadays, geostationary (GEO) satellite infrastructure plays a crucial role for the provisioning of IP services. Such infrastructure can provide ubiquity and broadband access, being feasible to reach disperse populations located worldwide within remote areas where terrestrial infrastructure can not be deployed.
Nevertheless, due to the expansion of the World Wide Web (WWW), new IP applications such as Voice over IP (VoIP) and multimedia services requires considering different levels of individual packet treatment through the satellite network. This differentiation must include not only the Quality of Service (QoS) parameters to specify packet transmission priorities across the network nodes, but also the required amount of bandwidth assignment to guarantee its transport. In this context, the provisioning of QoS guarantees over GEO satellite systems becomes one of the main research areas of organizations such as the European Space Agency (ESA). Mainly because, their current infrastructures require continuous exploitation, as launching a new communication satellite is associated with excessive costs. Therefore, the support of IP services with QoS guarantees must be developed on the terrestrial segment to enable using the current assets.
In this PhD thesis several contributions to improve the QoS provisioning over DVB-S2/RCS Broadband Satellite Systems have been developed. The contributions are based on cross-layer design, following the layered model standardized in the ETSI TR 102 157 and 462. The proposals take into account the drawbacks posed by GEO satellite systems such as delay, losses and bandwidth variations.
The first contribution proposes QoSatArt, an architecture defined to improve QoS provisioning among services classes considering the physical layer variations due to the presence of rain events. The design is developed inside the gateway, including the specification of the main functional blocks to provide QoS guarantees and mechanisms to minimize de delay and jitter values experienced at the application layer. Here, a cross-layer design between the physical and the network layer has been proposed, to enforce the QoS specifications based on the available bandwidth. The proposed QoSatArt architecture is evaluated using the NS-2 simulation tool. In addition, the performance analysis of several standard Transmission Control Protocol (TCP) variants is also performed. This is carry out to find the most suitable TCP variant that enhances TCP transmission over a QoS architecture such as the QoSatArt.
The second contribution proposes XPLIT, an architecture developed to enhance TCP transmission with QoS for DVB-S2/RCS satellite systems. Complementary to QoSatArt, XPLIT introduces Performance Enhanced Proxies (PEPs), which breaks the end-to-end semantic of TCP connections. However, it considers a cross-layer design between the network layer and the transport layer to enhance TCP transmission while providing them with QoS guarantees. Here, a modified TCP variant called XPLIT-TCP is proposed to send data through the forward and the return channel. XPLIT-TCP uses two control loops (the buffer occupancy and the service rate to provide optimized congestion control functions. The proposed XPLIT architecture is evaluated using the NS-2 simulation tool.
Finally, the third contribution of this thesis consists on the development of a unified architecture to provide QoS guarantees based on cross-layer design over broadband satellite systems. It adopts the enhancements proposed by the QoSatArt architecture working at the network layer, in combination with the enhancements proposed by the XPLIT architecture working at the transport layer.

One of the hardest tasks of a public key infrastructure (PKI) is to manage revocation. New
communication paradigms push the revocation system to the limit and an accurate resource assessment
is necessary before implementing a particular revocation distribution system. In this context, a precise
modeling of certificate revocation is necessary. In this article, we analyze empirical data from real
CAs to develop an accurate and rigorous model for certificate revocation. One of the key findings of
our analysis is that the certificate revocation process is statistically self-similar. The proposed model
is based on an autoregressive fractionally integrated moving average (ARFIMA) process. Then, using
this model, we show how to build a synthetic revocation generator that can be used in simulations
for resource assessment. Finally, we also show that our model produces synthetic revocation traces
that are indistinguishable for practical purposes from those corresponding to actual revocations.

his article presents QoSatAr, a cross-layer architecture developed to provide end-to-end quality of service (QoS) guarantees for Internet protocol (IP) traffic over the Digital Video Broadcasting-Second generation (DVB-S2) satellite systems. The architecture design is based on a cross-layer optimization between the physical layer and the network layer to provide QoS provisioning based on the bandwidth availability present in the DVB-S2 satellite channel. Our design is developed at the satellite-independent layers, being in compliance with the ETSI-BSM-QoS standards. The architecture is set up inside the gateway, it includes a Re-Queuing Mechanism (RQM) to enhance the goodput of the EF and AF traffic classes and an adaptive IP scheduler to guarantee the high-priority traffic classes taking into account the channel conditions affected by rain events. One of the most important aspect of the architecture design is that QoSatAr is able to guarantee the QoS requirements for specific traffic flows considering a single parameter: the bandwidth availability which is set at the physical layer (considering adaptive code and modulation adaptation) and sent to the network layer by means of a cross-layer optimization. The architecture has been evaluated using the NS-2 simulator. In this article, we present evaluation metrics, extensive simulations results and conclusions about the performance of the proposed QoSatAr when it is evaluated over a DVB-S2 satellite scenario. The key results show that the implementation of this architecture enables to keep control of the satellite system load while guaranteeing the QoS levels for the high-priority traffic classes even when bandwidth variations due to rain events are experienced. Moreover, using the RQM mechanism the user's quality of experience is improved while keeping lower delay and jitter values for the high-priority traffic classes. In particular, the AF goodput is enhanced around 33% over the drop tail scheme (on average).

One of the hardest tasks of a Public Key Infrastructure (PKI) is to manage revocation. Different revocation mechanisms have been proposed to invalidate the credentials of compromised or misbe-
having users. All these mechanisms aim to optimize the transmission of
revocation data to avoid unnecessary network overhead. To that end,
they establish release policies bas
ed on the assumption that the revoca-
tion data follows uniform or Poisson distribution. Temporal distribution
of the revocation data has a significant influence on the performance and
scalability of the revocation service. In this paper, we demonstrate that
the temporal distribution of the daily number of revoked certificates is
statistically self-similar, and that the currently assumed Poisson distribu-
tion does not capture the statistical properties of the distribution. None
of the commonly used revocation models takes into account this fractal
behavior, though such behavior has serious implications for the design,
control, and analysis of revocation protocols such as CRL or delta-CRL.

This article proposes XPLIT, a new architecture based on TCP cross-layering and splitting for optimizing the transport layer performance in a DVB-S2 satellite link that employs the ETSI QoS Broadband Satellite Multimedia Services (BSM) standard. The main novelty of our proposal is a complete architecture that perfectly fits this new DVB-S2/ETSI QoS BSM scenario. Our architecture includes the design of satellite-optimized cross-layer TCP protocol, called XPLIT-TCP that uses two control loops to properly manage the system load. The proposal has been implemented to be tested in the NS-2 simulator and we include the most interesting performance evaluation results, which show the excellent performance of our architecture for the intended scenario

The ability to communicate securely is needed for many network
applications. Public key infrastructure (PKI) is the most extended
solution to verify and confirm the identity of each party involved in any
secure transaction and transfer trust over the network. One of the hardest
tasks of a certification infrastructure is to manage revocation. Research
on this topic has focused on the trade-offs that different revocation mechanisms
offer. However, less effort has been paid to understand the benefits
of improving the revocation policies. In this paper, we analyze the
behavior of the oligopoly of certificate providers that issue digital certificates
to clients facing identical independent risks. We found the prices in
the equilibrium, and we proof that certificate providers that offer better
revocation information are able to impose higher prices to their certificates
without sacrificing market share in favor of the other oligarchs. In
addition, we show that our model is able to explain the actual tendency
of the SSL market where providers with worst QoS are suffering loses.

Vehicular Ad Hoc Networks (VANETs) require some
mechanism to authenticate messages, identify valid vehicles, and
remove misbehaving ones. A Public Key Infrastructure (PKI)
can provide this functionality using digital certificates. In PKI,
key management and corresponding issuance and revocation
of digital certificates is one of the key issues that have to be
solved. The IEEE 1609.2 standard states that VANETs will
rely on the use of certificate revocation lists (CRLs) to achieve
revocation. In this paper, we analyze the problems of using CRLs
in these type of networks. Moreover, we describe the Risk Aware
Revocation (RAR) mechanism that improves the traditional use of
CRLs. RAR takes advantage of the two distinct channel types in
VANETs to increase the freshness of the revocation information.
Moreover, RAR allows users to gauge the risk of operating in a
VANET when using CRLs.

Vehicular Ad-hoc Networks (VANETs) have been mainly motivated for safety applications, but non-safety applications
can also be very helpful to impulse vehicular networks. Among non-safety applications, video streaming services can
provide attractive features to many applications and can attract a great number of users. However, VANETs high mobility
characteristics and packet loss during communications blackouts difficult the deployment of video services in vehicular networks. In this paper, the performance of a video streaming service has been analyzed to study the deployability of a video on demand service in a highway environment for vehicular users. It has been analyzed the packet loss produced by network reconfiguration during handoffs and its influence in the video streamed quality.
Using Mobile IP without and with fast handoffs we have gauge the effects of mobility over the video transmission. We show that although fast handoffs techniques minimize blackouts, they limit the deployment of video streaming services in vehicular networks.

This paper presents a performance analysis of the TCP protocol considering the DiffServ architecture to provide Quality of Service guarantees working over a Digital Video Broadcasting - Second Generation (DVB-S2) satellite system. The analysis is carried out using the NS-2 simulator tool where
three TCP variants are considered: Sack TCP, Hybla TCP and Cubic TCP. The objective is to evaluate the TCP performance taking in to account goodput, friendliness and fairness
parameters and the most typical problems presented in a DVB-S2 satellite link such as delay, losses and bandwidth variations.

This paper presents an analysis of electromagnetic immunity of energy metering devices, using broadband power line communications (PLC) in low voltage (LV) supply networks with high levels of disturbance. Several tests have been carried out to characterize the behavior of PLC modems and couplers in presence of the most common types of disturbances and electromagnetic interferences (EMI) which can be expected in LV distribution networks.
The method exposed allows repeat the tests with different modems, communications wires and couplers. Thus it is possible to compare different elements between them and choose the best for every occasion.

This paper presents an adaptive algorithm for managing the weights of a weighted round robin (WRR) scheduler. The weights calculation depends on the capacity variations present in a Digital Video Broadcasting-Second Generation (DVB-S2) satellite link. The algorithm optimizes the bandwidth utilization while satisfying the QoS requirements for different traffic classes. The operation of the proposed algorithm is demonstrated by using the NS-2
simulator environment. The results show that the proposed adaptive WRR algorithm optimizes the bandwidth utilization while enforcing the priority level of each service class even in an extreme reduction of bandwidth caused by rain events.

Streaming consists in distributing media to large audiences over a computer network. Providing a streaming service for wireless mobile nodes presents many challenges. A peer-to-peer (P2P) solution has the big advantage of seamlessly scaling to arbitrary population sizes, as every node that receives the video, while consuming resources, can at the same time offer its own upload bandwidth to serve other nodes.
In this paper we present the design and implementation of NeuroCast: an unstructured P2P application for video streaming. NeuroCast implements a robust scheduling algorithm which minimizes the scheduling
delay. Moreover, given heterogeneous contents, delays and bandwidths. Thus, NeuroCast becomes suitable for wireless scenarios due to its capability to adapt to changing network conditions.